Name: China API 5CT K55 Casing Steel Pipe Manufacturers Suppliers Factory - Shenzhoutong Steel Pipe
Brand: Shenzhoutong
SKU: 318543115

Products Description

API 5CT K55 casing steel pipe is a high-strength seamless carbon steel casing manufactured in accordance with the API Specification 5CT (11th Edition). It is one of the most widely used casing grades for oil and gas well drilling, especially for surface, conductor and shallow intermediate casing strings. With a minimum yield strength of 379 MPa (55 ksi) and a minimum tensile strength of 655 MPa (95 ksi), K55 casing provides reliable structural support to the wellbore, protects the borehole from collapse, and isolates water zones and formation fluids. Our K55 casing is produced in both seamless and ERW (electric resistance welded) types, with BTC, LTC, STC and premium connections, covering outer diameters from 4-1/2" to 20".

echnical Specifications

Item	Specification
Standard	API Specification 5CT - 11th Edition (Casing and Tubing)
Grade	K55
Product type	Casing (also available as tubing on request)
Manufacturing	Seamless (hot-rolled) / ERW (electric resistance welded)
Outer diameter	4-1/2" to 20" (114.3 mm – 508.0 mm); also from 1.315" available
Wall thickness	Per API 5CT tables (e.g. 0.250" to 0.500" typical; per agreed size/weight)
Length	R1: 16–25 ft; R2: 25–34 ft; R3: 34–48 ft (per API 5CT length ranges)
Connection	P (Plain End), STC, LTC, BTC, Premium gas-tight connectors
End finish	Beveled / plain end, threaded & coupled as specified
Surface treatment	Black (as-rolled), or anti-rust oil / varnish; thread protectors on threaded ends
Yield strength	Min 379 MPa (55 ksi) / Max 552 MPa (80 ksi)
Tensile strength (min)	655 MPa (95 ksi)
Total elongation under load	0.5 %
PSL level	PSL-1 (Product Specification Level 1)
Marking	Per API 5CT (manufacturer, grade, size, heat number, date)
Test certificate	Mill Test Certificate per EN 10204 3.1 (3.2 available on request)

Chemical Composition (API 5CT K55 - typical range, weight %)

Element	Range / Max	Element	Range / Max	Element	Range / Max
C (Carbon)	0.34 – 0.39	P (Phosphorus)	≤ 0.020	Cr (Chromium)	≤ 0.15
Si (Silicon)	0.20 – 0.35	S (Sulfur)	≤ 0.015	Ni (Nickel)	≤ 0.20
Mn (Manganese)	1.25 – 1.50	Cu (Copper)	≤ 0.20	Mo (Molybdenum)	-
V (Vanadium)	-	-	-	-	-

Mechanical Properties

Property	Value (MPa)	Value (ksi)
Yield strength (min)	379 MPa	55 ksi
Yield strength (max)	552 MPa	80 ksi
Tensile strength (min)	655 MPa	95 ksi
Total elongation under load	0.5 %	-
Hardness limit	None specified	-
Sour service qualification	Not qualified (sweet service grade)	-
Heat treatment	Normalized / as specified per API 5CT	-

Product features

• Complies with API Specification 5CT (11th Edition)
• Grades: K55; also available in J55, N80, L80, P110
• Seamless & ERW manufacturing
• Connections: BTC, LTC, STC, Premium, Plain End
• Sizes: OD 4-1/2" to 20"; wall thickness per API 5CT
• Length ranges: R1, R2, R3 (per API 5CT)
• Yield strength: 379–552 MPa (55–80 ksi)
• Tensile strength min: 655 MPa (95 ksi)
• Full mill test certificates (EN 10204 3.1) available

Key Features & Benefits

Feature	Benefit
API 5CT compliant	Manufactured and tested to API Specification 5CT (11th Edition) - globally recognized OCTG quality standard.
High tensile strength	Min. tensile strength 655 MPa (95 ksi) supports Buttress (BTC) connections for near pipe-body tensile efficiency.
Versatile sizes	OD 4-1/2" to 20" with API-standard wall thickness; custom sizes by agreement.
Multiple connections	BTC, LTC, STC, Premium gas-tight and Plain End to match your well design and running requirements.
Seamless & ERW	Both seamless and ERW types available to fit different project budgets and specifications.
Full traceability	Heat number, grade and mill certificates provided for every heat / batch (EN 10204 3.1).
Quality tested	Chemical analysis, mechanical tests, hydrostatic test, flattening test, impact test and dimensional inspection.
Cost-effective	K55 offers an ideal strength/cost ratio for surface and conductor casing - reduces project casing cost.
Wide application	Suitable for surface, conductor, shallow intermediate casing in oil & gas wells; also water and geothermal wells.
Reliable supply	Factory-direct production with stable stock and on-time delivery worldwide.

Common Sizes & Weights

Nominal Size	OD (mm)	Weight (lb/ft)	Wall (mm)	ID (mm)	Typical Casing String
4-1/2"	114.30	11.60	6.35	101.60	Shallow production / liner
5-1/2"	139.70	17.00	7.72	124.26	Shallow production
7"	177.80	23.00	8.05	161.70	Production / intermediate
8-5/8"	219.08	32.00	8.94	201.20	Intermediate / surface
9-5/8"	244.48	36.00	8.94	226.60	Surface / shallow intermediate
13-3/8"	339.72	54.50	9.65	320.42	Surface casing (most common)
16"	406.40	75.00	11.13	384.10	Surface / conductor
20"	508.00	94.00	11.13	485.70	Conductor
Note	Each OD is produced in several weights. 13-3/8" runs up to 72 lb/ft and 20" up to 133 lb/ft for deeper setting. Ask us for the full API 5CT weight table.	-	-	-	-

Applications

Application	Description
Surface casing	Cements and supports the wellhead; protects shallow fresh-water zones; standard K55 application.
Conductor casing	Provides the first structural support at the top of the wellbore; large OD K55 common.
Shallow intermediate casing	Where collapse and burst loads are low; K55 covers the load case economically.
Shallow production casing	In shallow sweet-service production wells.
Oil & gas well drilling	General borehole support and zonal isolation during drilling and completion.
Water wells / boreholes	Casing for water wells and geothermal / borehole applications.
Sour service note	K55 is a sweet-service grade (not sour-service qualified). For H2S/sour conditions, use L80 or higher sour grades.

Connections & End Finishes

Connection	Description / Best for
P (Plain End)	Plain-end pipe without threads; for welded strings or cutting/threading on site.
STC (Short Thread Casing)	Round-thread connection; commonly paired with J55; economical for shallow strings.
LTC (Long Thread Casing)	Round-thread connection with longer thread length for improved joint strength.
BTC (Buttress Thread Casing)	Trapezoidal-thread connection achieving near pipe-body tensile efficiency; the standard pairing for K55 surface casing.
Premium gas-tight connectors	High-performance gas-tight premium connections for demanding applications (on request).
End finish options	Beveled ends, threaded & coupled (T&C), with thread protectors on each threaded end.
Note	For surface and conductor casing, API recommends K55 BTC. Confirm the connection type with your well engineering team before ordering.

Manufacturing Process & Quality Control

Stage	Description
Manufacturing process (seamless)	Steel billet heating → hydraulic piercing → reheating → elongation → periodic rolling → reheating → sizing → cooling → straightening → pipe cutting → inspection.
Manufacturing process (ERW)	Hot-rolled coil → uncoiling & leveling → forming → high-frequency resistance welding → heat treatment → sizing → cooling → straightening → cutting → inspection.
Quality control	Chemical composition analysis; mechanical property testing (yield, tensile, elongation); dimensional & wall-thickness inspection; hydrostatic pressure test; flattening test; impact test; visual inspection per API 5CT.
Certificates	Mill Test Certificate per EN 10204 3.1 (3.2 with third-party inspection available); API Monogram License (if applicable).
Third-party inspection	SGS, BV, TUV, Intertek or any third-party inspection accepted on request.
Traceability	Heat number and grade marked on every joint; full batch traceability.

Packaging, Shipping & Trade Terms

Item	Content
Packaging	Bundled with steel strips; ends protected with plastic caps / thread protectors; waterproof wrapping for export; sea-worthy packing.
Marking	Standard export marks per your requirement (grade, size, heat number, destination).
Port of loading	Tianjin Port, China (or as agreed).
Delivery time	【 e.g. 15–30 days after deposit, depending on size & quantity 】
MOQ	【 e.g. 20 tons / one container 】
Payment terms	T/T (30% deposit, 70% balance before shipment); L/C at sight; or as agreed.
Trade terms	FOB, CIF, CFR, EXW, DDP (as agreed).
Incoterms note	Confirm Incoterms, destination port and delivery date in your inquiry for an exact quotation.